1. Field of the Invention
The present invention relates to a camera module and a method for forming the camera module, and more particularly, to a camera module having an inner wall installed and a method for forming the camera module.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 illustrates a section view of a conventional camera module 10. The camera module 10 is applicable in a compact camera module (CCM). The camera module 10 includes a lens 12, an image sensor 14, a fixing module 17, an IR filter 19, a circuit board 20 and a plurality of connecting wires (only two connecting wires 24, 28 are shown on FIG. 1). The lens 12 is utilized for gathering light, and the image sensor 14 installed on the circuit board 20 (such as a printed circuit board (PCB)), includes a sensing region 34 for sensing the light gathered by the lens 12. The fixing module 17 is installed on the circuit board 20 for fixing the lens 12. The IR filter 19 is utilized for filtering unwanted infrared light, and only light of desired wavelengths can pass through. Furthermore, as shown in FIG. 1, the IR filter 19 is coupled to the fixing module 17, and the IR filter 19, the fixing module 17 and the circuit board 20 are grouped to form a sealed space 11. The connecting wires 24, 28 are respectively connected to the image sensor 14 and the circuit board 20 for transmitting sensing signals outputted by the image sensor 14 to the circuit board 20, or for transmitting control signals outputted by the circuit board 20 to the image sensor 14. In the manufacturing process, the fixing module 17, the image sensor 14, the IR filter 19, the circuit board 20 and the connecting wires 24, 28 are combined to form a lens holder module, after that the lens 12 is placed onto the lens holder module.
In general, the conventional camera module 10 has the following disadvantages. First, the sensing region 34 may be affected by particles. More specifically, during the manufacturing process of the camera module 10, flux is utilized on some components such as soldering the connecting wires 24, 28 onto the circuit board 20, residue may remain around the connecting wires 24, 28 on the circuit board which cannot be cleaned. As a result, the residue remains in the sealed space 11, and as time passes, the residue may form into tiny particles, hence the sensing region 34 maybe affected by the particles in the sealed space 11, which affects the sensing quality.
A second disadvantage of the conventional camera module 10 involves reliability. The reliability of the sensing region 34 can be reduced due to moisture. Please refer to FIG. 2. FIG. 2 illustrates a top view of a bearing surface of a fixing module 17 and a circuit board 20, wherein a portion marked by oblique lines is the bearing surface. As illustrated in FIG. 1 and FIG. 2, the fixing module 17 supports the lens 12 and the IR filter 19, a surface area of a bearing surface which is a connected portion of the fixing module 17 and the circuit board 20 is very narrow, the width is usually only 0.4 mm. However, since the narrow bearing surface is required to support the weights of the lens 12, the IR filter 19 and the fixing module 17, therefore the connection portion of the fixing module 17 and the circuit board 20 may crack, causing instability in the structure of the camera module 10. Additionally, moisture can easily enter the sealed space 11 through the crack in the connection portion of the fixing module 17 and the circuit board 20, which affects the functions of the sensing region 14.
A third disadvantage is packaging yield. When the IR filter 19 is coupled to the fixing module 17, there is a possibility that air is disturbed and moved such that the particles near the sensing region 14 will fall onto the sensing region 14, which can cause the packaging yield to decrease; furthermore, when fixing the fixing module 17 on the circuit board 20, it is easy to compress the connecting wires 24, 28, which can also cause the packaging yield to decrease.
A fourth disadvantage is that the size of the lens is limited by the size of the fixing module, which does not always meet manufacturers' requirement to customize or redesign. After packaging the lens holder module (which includes the fixing module 17, the image sensor 14, the IR filter 19, the circuit board 20 and the connecting wires 24, 28), when the lens 12 is placed onto the lens holder module, the size of the lens is limited by the size of the fixing module 17, in another words, if the camera module 10 is to use a different sized lens, it is impossible to place the different sized lens directly onto the lens holder module without breaking the packaged lens holder module, thus the manufacturers' requirement for customization or redesigning cannot be met. This also indirectly increases the cost of manufacturing the camera module 10.
A fifth disadvantage is the limitation in the manufacturing material for the fixing module 17. In manufacturing the camera module 10, if a conventional hot bar process is required, as the circuit board 20 will directly pass heat to the fixing module 17, therefore the fixing module 17 is required to sustain high temperature, and only high temperature tolerant material can be utilized to prevent the fixing module 17 from deformation which can affect the fixation of the lens 12.